Mobile robots are becoming increasingly commonplace and are used in such diverse fields as space exploration, lawn mowing and floor cleaning. The last decade has seen particularly rapid advancement in the field of robotic floor cleaning devices, especially vacuum cleaners, the primary objective of which is to navigate a user's home autonomously and unobtrusively whilst cleaning the floor.
In performing this task, a robotic vacuum cleaner has to navigate the area which it is required to clean and to avoid colliding with obstacles whilst doing so. Typically, a robot vacuum cleaner will feature a movable bumper which forms part of the shell of the robot and one or more sensors arranged to detect movement of the shell relative to the chassis of the robot. Examples of such an approach are described in EP1997418A2 and U.S. Pat. No. 7,647,144B2.
Although bumpers function adequately as a means for detecting when the robot comes into contact with obstacles, they add significant complexity to the robotic system as a whole. Firstly, bumpers usually take the form of a wrap-around shell part that conforms around at least a portion of the robot so that it is able to detect collisions over a wide angular range. Also, such a bumper typically projects from the body of the robot to provide it with clearance to move in response to a collision, and to trigger a sensing mechanism as a result of that movement. This increases the size of the robot and also adds weight.
Furthermore, in practice bumper assemblies tend to be rather fragile which reduces the robustness of the robot.